Page 389 - The Veterinary Laboratory and Field Manual 3rd Edition

358 Susan C. Cork, Willy Schauwers and Roy Halliwell

will be through direct contact, through skin if
animals are being treated with insecticides, or
through ingestion if they are feeding in fields
where the chemicals have been applied. In the
case of agrochemicals or pesticides, informa-
tion about the product should be requested,
and samples collected (Table 7.7). If a natural or
manufactured poison is suspected to have been
consumed, vomitus or stomach content are very
important samples to collect, as well as blood
and urine from affected but still alive animals.
In dead animals, ocular fluid collected into a
Figure 7.16 Hind limbs from beef cattle suffering sterile syringe is useful, and often is more read-
from severe ergotamine toxicity, show the classic ily obtained than blood which will be clotted.
lesions with the lost blood supply resulting in tissue Additional tissue samples should include pieces
death, with hooves and feet falling off. of liver, kidney, muscle, fat and brain, stored in
plastic containers and frozen, with thin sections
Globally, these SGARs are poisoning large (< 4 mm thick) placed into formalin, if that is
numbers of wildlife, heavily affecting avian and available.
terrestrial scavengers, the species that have his- Death due to inhalation of highly toxic gases
torically played the role of nature’s clean-up such as hydrogen sulphide, carbon monoxide
crews. As well, birds of prey such as owls, fal- and cyanide, leaves no residues, and very little
cons and hawks, feed on live rodents therefore physical evidence beyond possible changes in
controlling their populations. However, they are blood colour (bright red in the case of CO poi-
also seriously affected by rodenticide poisoning soning). In these situations, the per-acute nature
since the poisoned, but still alive rodents, are of the poisoning (animals die within minutes),
the easiest to catch. Studies have shown 80% and a possible source of such gases, like a sew-
to 100% of these raptors found on agricultural age lagoon, or a gas pipe, should be obvious.
landscapes have rodenticide residues in their Toxicology facilities are often difficult to find
tissues, with 30 to 35% of those having lethal at the district level, but samples may be sub-
levels (Smits and Naidoo, 2018 and references mitted to a referral centre. It is not possible to
therein). Eagles, vultures, wolves, coyotes, test for all known toxicants in every sample, nor
hyenas, lions and other perceived threatening would it be cost effective to test unless the per-
or nuisance wild and domestic animals have all son submitting has a reasonably good idea as to
fallen victim to secondary poisoning, uninten- what the poison could be. It is essential that the
tionally or by design through poisoned baits. veterinary or animal health officer collects and
The examination and analysis of tissues and submits the proper samples to the referral lab.
body fluids for the presence of naturally occur- With toxicology, it is especially important that
ring toxins and man-made toxicants, is very a good case history has been taken with details
important to get a diagnosis (Table 7.7). In of clinical signs, number of animals affected, a
cases of sudden death, with no obvious expla- description of the environment where the ani-
nation, such as trauma, it is logical and wise to mals were found, and note any recent changes in
consider a toxic cause and plan to collect use- diets, or agrochemical treatment of crops in the
ful samples. Most exposure to toxic compounds area, or run-off from nearby industrial activity,

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